Abstract
A mixture of equal amounts of calcined flint clay and kaolinite was thoroughly ground (mixture 2). A 50 % alumina-silica refractory brick [HE 50 (2)] was prepared by firing this mixture. Physical and chemical properties and mineralogical composition of the ground mixture and the brick were examined. They were compared with the properties of a mixture of calcined flint clay and kaolinite of which each component was ground prior to mixing (mixture 1) and of a brick obtained from this mixture [HE 50 (1)]. Amorphous material, surface area and water sorption are higher in mixture 2 than in mixture 1. By grinding, small particles of kaolinite adhere to the larger particles. Mullitization in HE 50 (2) is greater than in HE 50 (1); this leads to a lower porosity. Differencesbetween the two bricks seem to be associated with differences between the fine structures of the two mixtures.
